My room isn't tidy. It needs a good solid going over. I think it affects me psychologically when my room is messy. It sort of tells me that even though I'm giving off the appearance to everyone else that I'm a really together dude in reality I'm still the same little moron my Dad used to tell off for being untidy and disorganised. I've just fallen on my feet, for the moment, and ultimately I'll get found out at some stage.
The obvious solution to this is of course to tidy my room. I think part of the reason I don't do this is because I'm expressing inner turmoil to myself. I often feel a bit of a fraud when my room is tidy and my life is running neatly. It's not me. I honestly sometimes have difficulty getting to sleep in a tidy, spotless, well ordered room. It fractures my personal identity. It's a bit like when I loose weight and get genuinely slim, I can't help but feel I've betrayed the fellow pie-eaters of this world by escaping their number and pretending to be normal.
There should be more research done into this. We're territorial animals, perhaps having a messy room is our way of marking our territory. It's safer than crapping all over it and reasonably effective. 2000AD comics, rubbish CD's that only I like and a massive pile of laundry - all indicators that you're in my room. My little nest!
So, my untidy room is in a way an expression of inner turmoil, and a symbol of my own animalistic habits. That and the expression of the fact that sometimes in life I simply can't be arsed.